Heat exchangers are used for heating and cooling air in outdoor units for air-conditioning devices, heat-source units for hot-water-supplying devices, and the like. Types of heat exchangers include layered heat exchangers such as given in, e.g., Japanese Laid-Open Patent Application No. 2010-2138, in addition to types in which heat-transfer tube having a circular cross-section are inserted into fins. Layered heat exchangers have a configuration in which flat heat-transfer tubes are positioned at a plurality of stages in a state in which a flat part, which expands in the shape of a horizontal surface, faces a vertical direction, where fins are positioned in ventilation spaces sandwiched by adjoining flat heat-transfer tubes.
There also exist heat exchangers such as given in Japanese Laid-Open Patent Application No. 2005-3350. A plurality of louvers are provided to the fins of the heat exchanger according to Japanese Laid-Open Patent Application No. 2005-3350 at predetermined intervals along a direction of air flow. In particular, multiple types of louvers having different louver widths are positioned in a mixed fashion in Japanese Laid-Open Patent Application No. 2005-3350.